Different methods of assessing nicotine-induced antinociception may engage different neural mechanisms

Abstract

Two methods were used to assess nicotine-induced antinociception: tail withdrawal from a hot water bath and hind paw withdrawal from a hotplate. Nicotine doses which produced 75-80% maximum response were 0.75 mg/kg (free base) for tail withdrawal and 0.35 mg/kg for paw withdrawal. The peripheral blocker chlorisondamine (0.1 mg/kg, SC) and the central antagonist, mecamylamine (1 mg/kg, SC) were each effective in blocking nicotine-induced increases in tail withdrawal latencies, suggesting that this effect of nicotine depends on either the action of nicotine at peripheral receptors or the functional integrity of those receptors. In contrast, nicotine-induced increases in paw withdrawal latencies were blocked by mecamylamine but not by chlorisondamine, even at other agonist/antagonist dose combinations. The results indicate that these two effects of nicotine involve at least partially separate pathways and may reflect a different mix of the antinociceptive and motor depressing effects of nicotine.

The Analgesia-Enhancing Component of Ingested Amniotic Fluid Does Not Affect Nicotine-Induced Antinociception in Naltrexone-Treated Rats

“…E-nwil: kri,t;lll.dacsu.hll I'Ll 10.cdu ments. It should be noted, however, that peripherally injected chlorisondamine did successfully block nicotine antinocicep tion when tested in a hot-water tail-dip assay, suggesting the possible presence of a peripheral component to nicotine's ef fects on the tail withdrawal response (5). A central site of ac tion is further indicated by studies showing that nicotine induced antinociception is greatest after injection into the pe dunculopontine tegmental nucleus of the mesopontine teg mentum, areas of the ventral and posterior medulla, the cen tral gray, or the subarachnoid space (2, [9][10][11]24).…”

“…Peripherally injected chlorisondamine. it bisqua ternary peripheral antagonist specific for nicot inc, completely failed 10 block niCOline-induced antinocieeptioll in the hot plate assay (5), the assay used in the present set of experiRcqucsts 1"01' rc'prinls should be ,Iddrcsscd to Mark B. Krista!. Department of Psychology.…”

“…We decided to use a hot-plate assay in the present experiment because it is frequently used to assess antinociception produced by nicotine (5,(9)(10)(11)20,22,24). There fore, it was important to demonstrate the presence of POEF enhancement of opiate-mediated antinociception using the hot-plate assay before testing for POEF enhancement of nico tine-induced antinociception.…”

The Lysophosphatidylinositol Receptor GPR55 Modulates Pain Perception in the Periaqueductal Gray

“…Although we observed a pronociceptive effect of GPR55 activation in male rats, it is interesting that studies using global deletion of GPR55 indicate an impact on nociception in the hot-plate test in only female animals (Staton et al, 2008;Wu et al, 2013). Because the hot-plate test evaluates pain as a result of supraspinal sensory integration (Caggiula et al, 1995;Rubinstein et al, 1996), a putative explanation may reside in the fact that GPR55 is expressed at pain-relevant supraspinal sites other than the PAG (Henstridge et al, 2011), where the effects of its activation may interfere with sexual hormone-mediated signaling.…”

Tobacco/nicotine and endogenous brain opioids

“…There is an extensive literature that acute and chronic nicotine increases thresholds for nocioceptive responses in either mice or rats (Aceto et al, 1983;Anderson et al, 2004;Bannon et al, 1998;Caggiula et al, 1995;Carstens et al, 2001;Christensen and Smith, 1990;Craft and Milholland, 1998;Damaj et al, 1993Damaj et al, , 1998Damaj et al, , 1999Iwamoto, 1989;Iwamoto, 1991;Khan et al, 1998;Martin et al, 1990;Phan et al, 1973;Rogers and Iwamoto, 1993;Sahley and Berntson, 1979;Tripathi et al, 1982;Yang et al, 1992;Zbuzek and Chin, 1994;Decker et al, 2001Decker et al, , 2004Vincler, 2005). These basic science antinocioceptive studies are interpreted as evidence that nicotine is analgesic.…”